1. Field of the Invention
The present invention is a means of controlling the directional properties of sound. More specifically the invention is a means of altering the shape and direction of a wave front by providing separate delaying paths for different parts of the wavefront, which causes refraction of the wave where the paths recombine.
Devices used to control the directional properties of sound fall mainly into two categories: devices to increase the directivity of microphones, and devices to decrease the directivity of loudspeakers. The present invention falls mainly into this latter category. A third, structurally related category is represented by the acoustic delay line, which preserves the directional properties of an acoustic wave while displacing it in time and space.
2. Description of the Prior Art
Acoustic refractors that were known heretofore, such as the slant plate, perforated plate and corrugated plate varieties, cause reflections of the wave when it enters the refractor, and again when it emerges from the refractor. The acoustic refractor herein disclosed is designed to produce smaller reflections than previous refractors, and can more conveniently be arranged to provide large refraction angles.